Broadly Reactive Antibodies Against Chimeric Virus-Host Antigens

描述(由申请人提供)： HIV-1病毒从细胞膜上发芽，并将宿主蛋白合并到其包膜中。在这项提案中，我们讨论了这些宿主蛋白对艾滋病毒免疫的影响。我们将检验这一假设，即在HIV感染期间，抗体是针对部分由宿主蛋白和部分由病毒环境糖蛋白形成的表位而产生的，并且这些抗体具有广泛的抗病毒活性。因此，我们提出了一个非常新颖的概念，即嵌合抗原是病毒免疫的一个特征，它由宿主和病毒组件之间稳定或瞬时的界面组成。如果我们的假设是正确的，则可以通过将病毒蛋白与保守的宿主蛋白相结合来制造免疫原，从而允许高比例的保守决定簇。此外，由于嵌合抗原可能是构象的，因此可以构建基于来自宿主/病毒界面的保守结构的独特的免疫原。我们将完成以下具体目标：1)筛选与嵌合抗原结合的单抗。我们将筛选抗病毒样颗粒(VLP)或表达Env的细胞的单抗(来自HIV感染者)，这些细胞有或没有存在于病毒粒子表面的宿主蛋白。宿主蛋白的表达将受到RNA干扰(RNAi)的调控。只与VLP结合的单抗或同时表达Env和感兴趣的宿主蛋白的细胞的单抗将被进一步评估；2)确定针对嵌合抗原的单抗的抗病毒功能。将测试抗体对一组HIV-1毒株的中和作用和抗体依赖的细胞介导的病毒抑制作用。由于我们将筛选多达1000个单抗，并考虑至少20个宿主蛋白作为与Env形成表位的合作伙伴，因此我们将有很好的机会找到嵌合抗原，如果它们存在的话。此外，我们的筛查范围将提供对负面结果的信心。因此，我们的方法旨在充分探索针对嵌合抗原的抗体在HIV感染过程中发生的假设，我们将获得它们存在或不存在的强有力证据。如果我们的研究成功，我们的研究将导致范式的转变，从抗病毒抗体反应总是针对唯一的病毒表位的概念转向由病毒和宿主组成的表位的绝对新的概念。此外，我们的嵌合抗原的新概念可能会产生新的、广泛的抗病毒单抗和新的免疫原，从而引起广泛的抗病毒反应。发现嵌合抗原可以克服有效疫苗的看似难以克服的障碍，从而对艾滋病毒预防产生深远影响。开发艾滋病毒疫苗的一个主要障碍是缺乏能够引起广泛的抗病毒抗体反应的免疫原。我们提出了一种非常新颖的方法来发现这种免疫原。如果成功，这项研究可能会直接导致预防艾滋病毒感染的疫苗。

DESCRIPTION (provided by applicant): HIV-1 buds off cell membranes and incorporates host proteins in its envelope. In this proposal, we address the impact these host proteins have on HIV immunity. We will test the hypothesis that during HIV infection, antibodies are made against epitopes formed partly by host proteins and partly by viral Env glycoproteins and that such antibodies have broad anti-viral activity. Thus, we propose the very novel concept that chimeric antigens, consisting of a stable or transient interface between host and viral components, are a feature of viral immunity. If our hypothesis is correct, immunogens could be made by combining viral proteins with conserved host proteins, thereby allowing a high proportion of conserved determinants. In addition, since chimeric antigens are likely to be conformational, unique immunogens based on conserved structures derived from host/virus interfaces could be constructed. We will accomplish the following specific aims: 1) Screen mAbs for binding to chimeric antigens. We will screen mAbs (from HIV-infected subjects) against virus-like particles (VLPs) or Env-expressing cells with or without host proteins known to occur on virion surfaces. Expression of host proteins will be regulated by RNA interference (RNAi). mAbs binding only to VLPs or cells expressing both Env and a host protein of interest will be evaluated further; 2) Determine the antiviral function of mAbs directed against chimeric antigens. Antibodies will be tested for neutralization and antibody-dependent cell-mediated virus inhibition against a panel of HIV-1 strains. Since we will screen as many as 1,000 mAbs and consider at least 20 host proteins as partners with Env in forming epitopes, we will have an excellent chance of finding chimeric antigens should they exist. Moreover, the extent of our screening will provide confidence in a negative result. Thus, our methods are designed to fully explore the hypothesis that antibodies against chimeric antigens occur during HIV infection, and we will gain strong evidence of their presence or absence. If successful, our research will result in a paradigm shift away from the concept that anti- viral antibody responses are always directed against uniquely viral epitopes and toward the decidedly new concept of epitopes made from virus plus host. Moreover, our novel concept of chimeric antigens may yield new, broadly anti-viral mAbs and novel immunogens that elicit broadly anti-viral responses. Discovering chimeric antigens could have a profound impact on HIV prevention by overcoming seemingly intractable obstacles to an effective vaccine. A major obstacle to the development of an HIV vaccine is the lack of an immunogen that elicits broadly anti- viral antibody responses. We propose an exceptionally novel approach to discover such immunogens. If successful, this research may lead directly to a vaccine that prevents HIV infection.